# Sheep Flushing Before Breeding: Feed Planning and Limits ## Key Takeaways - Flushing strategically elevates energy intake for 3-4 weeks pre-breeding to increase ovulation rate and lambing percentage by stimulating luteinizing hormone (LH) pulse frequency and follicular development. - Optimal response to flushing is observed in ewes with a body condition score (BCS) of 3.0-3.5 on a 5-point scale; overconditioned ewes (>3.5 BCS) show diminished or no reproductive gain and increased risk of metabolic disorders. - Feed planning must consider forage energy density and pre-flushing ewe body condition, with gradual concentrate introduction (over 5-7 days) essential to prevent subacute ruminal acidosis and digestive upset. - Flock records detailing ewe age, parity, and previous lambing performance are critical for tailoring flushing intensity and identifying individual ewes that may require different nutritional strategies. - Monitoring involves weekly BCS assessment and, in a representative sample, weekly weight gain to ensure a mean daily gain of 50-150 grams; deviations warrant ration adjustment. - Flushing is a short-term intervention; prolonged high-energy feeding or abrupt withdrawal can lead to pregnancy toxemia, dystocia, and reduced fertility in subsequent cycles. --- Flushing is the strategic elevation of energy intake in ewes for three to four weeks before breeding to increase ovulation rate and lambing percentage. The practice works by stimulating luteinizing hormone secretion and enhancing follicular development, as confirmed by physiological studies using GnRH antagonists ([Reduction of the developmental competence of sheep oocytes by inhibition of LH pulses during the follicular phase with a GnRH antagonist](https://api.elsevier.com/content/abstract/scopus_id/0032836998)). The efficacy of flushing is constrained by three factors: forage energy density, pre-flushing body condition, and individual flock records. Without these limits, flushing risks overconditioning, metabolic disorders, or no reproductive gain. The [Merck Veterinary Manual](https://www.merckvetmanual.com/) emphasizes gradual concentrate introduction to avoid digestive upset. | Aspect | Key Points | Limits | |--------|------------|--------| | Objective | Raise ovulation rate and lambing percentage | Overconditioned ewes show no response | | Timing | 3-4 weeks before ram exposure | Delayed start reduces follicle recruitment | | Feed sources | High-energy grains, legume pasture | Low-quality forage fails to provide energy | | Monitoring | [Body condition scoring](/knowledge/animal-farming/farm-management/body-condition-scoring-a-tool-for-feed-management) and feed records | Incomplete records cause over- or underfeeding | ## Physiological Basis and Planning Decisions Flushing elevates luteinizing hormone (LH) pulse frequency, driving follicle recruitment. Suppressing LH with a GnRH antagonist reduces oocyte competence, confirming that LH drive is a key mediator of flushing effects ([Reduction of the developmental competence of sheep oocytes by inhibition of LH pulses during the follicular phase with a GnRH antagonist](https://api.elsevier.com/content/abstract/scopus_id/0032836998)). Ovarian transcriptome studies link energy metabolism genes to prolificacy, showing that nutrient availability directly affects ovarian function ([Integrated ovarian mRNA and miRNA transcriptome profiling characterizes the genetic basis of prolificacy traits in sheep](https://api.elsevier.com/content/abstract/scopus_id/85041055373)). The classic liveweight-productivity relationship demonstrates that ewes with body condition scores of 3.0 to 3.5 on a 5-point scale respond best to flushing, whereas very thin or overfed ewes show diminished gains ([Liveweight-productivity relationships in sheep](https://api.elsevier.com/content/abstract/scopus_id/84909690301)). Body condition scoring six weeks before breeding identifies candidates. Ewes with scores below 2.5 need a gradual energy increase to reach an optimal score of 3.0 to 3.5. Ewes at scores of 3.5 or above do not benefit from additional energy and may suffer reduced fertility if overfed. Recent flushing trials confirm condition score as the single best predictor of response, with overconditioned ewes showing lower pregnancy rates ([PubMed record 39720830](https://pubmed.ncbi.nlm.nih.gov/39720830/), [PubMed record 38982684](https://pubmed.ncbi.nlm.nih.gov/38982684/)). Forage testing for metabolizable energy guides supplementation. Forages with low digestible energy, such as mature hay or drought-stressed pasture, cannot support a flushing response without concentrate feeding. Conversely, high-quality legume pastures may provide sufficient energy without grain addition. The [FAO Animal Production and Health](https://www.fao.org/animal-production/en/) advises balancing concentrates with fiber to prevent subacute ruminal acidosis, which reduces intake and may cause laminitis or liver abscesses. ## Management Framework for Feed Limits Flock records of ewe age, parity, previous lambing performance, and body weight changes allow producers to tailor flushing intensity. Ewe lambs and aged ewes have different energy requirements and may respond poorly to standard flushing regimens. The [USDA National Animal Health Monitoring System](https://www.aphis.usda.gov/livestock-poultry-disease/nahms) emphasizes that record-based management improves reproductive efficiency and reduces feed waste. Without such records, flushing becomes a blind practice that risks both under- and overfeeding. Exceeding feed limits causes overconditioning, which impairs gonadotropin secretion and lowers ovulation rates. Excessive body fat also increases the risk of perinatal complications, including dystocia and pregnancy toxemia late in gestation. The [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) includes guidelines for avoiding metabolic disease through controlled feeding. Underfeeding during flushing fails to elevate LH pulse frequency, leaving ovulation rates unchanged. Professional veterinary advice is warranted when flock records are absent or forage quality is uncertain. ### Facilities and Environmental Considerations Flushing involves a planned increase in nutritional plane 2 to 4 weeks before ram introduction. The success of this intervention depends on the flock’s ability to access, consume, and metabolize additional energy without stress. Feed delivery facilities must provide adequate feeder space to prevent subordinate ewes from being bullied away from the supplementary feed. Overcrowded pens or poor feeder design increase competition and limit intake in thin ewes, which often need flushing most. The environment should minimize thermal stress, high ambient temperatures depress feed intake and can blunt the flushing response. Well,ventilated, shaded areas with clean water are essential because even short,term water restriction reduces voluntary feed consumption. The housing or paddock layout should allow easy observation of each ewe’s body condition and feed,bunk behavior, enabling early detection of individuals that fail to gain or that become overly aggressive at the feeder. Reference guidelines from the [FAO Animal Production and Health](https://www.fao.org/animal-production/en/) emphasize that any nutritional change should be implemented within an existing low,stress management routine. ### Forage and Nutritional Limits The primary limit to flushing is forage quality. In many production systems the available pasture or hay determines whether the target energy intake can be achieved. If the basal forage is low in digestible energy, the ewe may be unable to consume enough bulk to reach the desired plane of nutrition, or she may fill her rumen with indigestible fiber that does not support the metabolic shift required for increased ovulation rate. Supplementing with a concentrated energy source,such as whole grains, pellets, or high,quality legume hay,becomes necessary, but the amount must be carefully controlled. Over,feeding energy before breeding can deposit excessive fat in the pelvic cavity, mechanically impairing ovulation and implantation. [Liveweight,productivity relationships in sheep](https://api.elsevier.com/content/abstract/scopus_id/84909690301) (1962) established that a moderate gain of 2,4 kg in mature ewes during the pre,breeding period improves prolificacy, but ewes already at or above optimal condition show little or no response and may even conceive fewer lambs. The [Reduction of the developmental competence of sheep oocytes by inhibition of LH pulses during the follicular phase with a GnRH antagonist](https://api.elsevier.com/content/abstract/scopus_id/0032836998) (1999) demonstrated that the flushing effect is mediated through luteinizing hormone pulse frequency, a sudden, extreme energy surplus can disrupt the gonadotropin signal and compromise oocyte quality. Therefore, the nutritional limit is defined not by a fixed number of kilograms of feed but by the ewe’s current body condition, the energy density of the forage base, and the metabolic trajectory that the flock can sustain without sharp dips in intake. ### Feed Planning and Condition Records Production,stage decisions for flushing must be individualized using body condition scoring and, where possible, liveweight records. [Effect of feed flushing during summer season on growth, reproductive performance and blood metabolites in Malpura ewes under semiarid tropical environment](https://api.elsevier.com/content/abstract/scopus_id/84927166527) (2012) showed that flushing improved lambing percentage in ewes with a pre,flushing condition score of 2.5 or lower on a 5,point scale, whereas ewes scoring 3.5 or higher gained no reproductive benefit. Tailoring the flushing ration requires flock records that capture condition scores at weaning, 6 weeks before breeding, and at ram introduction. The same dataset allows the manager to identify categories of ewes,thin yearlings, primiparous dams, or aged ewes with worn teeth,that may need a longer flushing period or a different energy source. The [Integrated ovarian mRNA and miRNA transcriptome profiling characterizes the genetic basis of prolificacy traits in sheep](https://api.elsevier.com/content/abstract/scopus_id/85041055373) (2018) confirms that genetic variation in ovulation rate interacts with nutrition, consequently, a one,size,fits,all feeding plan disregards individual heredity and can depress embryo yield in high,prolificacy lines. Records must also document the ram joining date and the first 18,day cycle to correlate flushing inputs with conception rates. The [Effect of mating system, flushing procedure, progesterone dose and donor ewe age on the yield and quality of embryos within a MOET program in sheep](https://api.elsevier.com/content/abstract/scopus_id/0034133078) (2000) underlines that older donor ewes respond less robustly to flushing, reinforcing the need for age,specific feed plans. ### Welfare and Metabolic Risks Sudden changes in feed composition or volume can cause ruminal acidosis, enterotoxemia, or founder. Forage should account for at least 60% of the dry matter intake during flushing to buffer the rumen pH. The [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) and the [Merck Veterinary Manual](https://www.merckvetmanual.com/) stress that any nutritional intervention must avoid conditions that induce pain or distress. Offer the concentrate gradually over 5,7 days, and never increase the allowance by more than 0.2 kg per head per day. Over,ambitious flushing can precipitate pregnancy toxaemia if the same high,energy ration is continued after conception and then abruptly withdrawn, the feeding plane should be reduced to a moderate maintenance level once the breeding period ends. Worker safety concerns include grain dust inhalation when mixing or pouring feed and the risk of crushing when handling ewes in tight pens during condition scoring. Personal protective equipment and low,stress handling protocols reduce injury rates. [Food safety](/knowledge/bacteria/livestock-bacteria/cooking-chicken-bacteria-prevention) is not directly relevant at the pre,breeding stage, but good record,keeping for any feed additives or medications used during flushing is a prudent biosecurity practice consistent with [USDA APHIS Livestock and Poultry Disease](https://www.aphis.usda.gov/livestock-poultry-disease) guidelines for traceability. ### Failure Patterns and Practical Monitoring Flushing fails most often because of inadequate energy density in the supplement, insufficient duration, or misidentification of ewes that do not need flushing. Thin ewes that do not gain at least 1.5 kg over the flushing period are unlikely to show a rise in ovulation rate. Conversely, fat ewes that lose no condition may have been over,fed, wasting resources and increasing the risk of dystocia later. The [PubMed record 39720830](https://pubmed.ncbi.nlm.nih.gov/39720830/) (a review of reproductive performance) emphasizes that environmental stress,transport, mixing, or extreme weather,can override any nutritional benefit. Monitor weight gain weekly in a representative sample (20,30 animals per flock) and adjust the ration if the mean daily gain is below 50 grams or above 150 grams. Body condition scoring every 10 days provides a check on individual variation. Palpation of fat cover over the loin and tail head, combined with visual appraisal, is more reliable than weight alone for cull or thin ewes. Practical flock records should include the date of supplement introduction, the total kilograms of concentrate fed per pen per day, and the number of ewes observed at the feeder. Any ewe that consistently fails to come to the feed trough may need separation and hand,feeding. The [PubMed record 41710937](https://pubmed.ncbi.nlm.nih.gov/41710937/) (an early but foundational study on flushing) notes that the response is greatest in flocks with a 60,80% overall conception rate, if the baseline pregnancy rate is already above 85%, flushing may produce no measurable benefit and should be reevaluated. Monitoring the lambing rate the following year, broken down by flushing treatment, allows the manager to refine feed planning iteratively, always respecting the limits set by forage supply, ewe condition, and accurate records. ## Health Monitoring and Biosecurity During Flushing Flushing alters the ewe’s metabolic and endocrine state, which can unmask subclinical infections or nutritional imbalances. Close observation is required throughout the 2- to 4-week flushing period. Evaluate feed intake, body condition, and fecal consistency daily. Any drop in appetite, loose stools, or lethargy warrants immediate investigation because such signs may indicate grain overload or acidosis from concentrate supplementation. The [Merck Veterinary Manual](https://www.merckvetmanual.com/) describes that sudden introduction of high-energy feeds disrupts rumen pH and can precipitate acute indigestion. Body condition score (BCS) should be monitored weekly, ewes that lose condition during flushing or that fail to respond within 10 days should be examined for underlying disease such as chronic parasitism, dental lesions, or metabolic dysfunction. Biosecurity measures must be maintained even during this short-term nutritional intervention. Flushing often involves bringing feedstuffs onto the farm, which can introduce weed seeds, molds, or pathogens. Store all concentrate feeds in clean, sealed containers away from rodents and birds. Use separate equipment for handling flushed feed to avoid cross-contamination with routine rations. The [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) emphasizes that shared feeding equipment can become a fomite for diseases such as scrapie or bluetongue when animals are pooled into flushing groups. If flushing is conducted as a group-management strategy instead of individually, ensure that all ewes in the group have equivalent health status. Quarantine any replacement ewes for at least 30 days before they join the flushed cohort. ## Diagnostic and Veterinary Escalation Flushing-induced ovulation responses can be assessed via ultrasound at 30 to 35 days post-mating to determine pregnancy rate and prolificacy. However, the ability of flushing to raise ovulation rate is not uniformly predictable. Recent reviews (e.g., [PubMed record 39720830](https://pubmed.ncbi.nlm.nih.gov/39720830/)) note that the magnitude of response depends on ewe age, breed, and pre-flushing BCS. Ewes with BCS > 4.0 on a 5-point scale often show minimal or no improvement, those with BCS < 2.5 may have a delayed response that is confounded by poor general health. In such cases, veterinary diagnostic workup,including fecal egg counts, serum beta-hydroxybutyrate for negative energy balance, and ovarian ultrasound to assess follicular activity,is warranted before assuming the poor response is due to improper feed planning. If conception rates remain low after multiple flushing attempts in a flock, consider submitting serum samples for trace mineral analysis (selenium, copper, zinc) and testing for infectious causes of infertility such as *Chlamydia abortus* or *Brucella ovis*. The __MASK_25__ portal provides guidelines for diagnostic submission under the National Animal Health Monitoring System. Furthermore, __MASK_26__ suggests that ovarian gene expression patterns related to prolificacy are fixed early in life, thus, poor genetic potential cannot be overcome by flushing alone. Veterinarians should counsel producers that flushing is an adjunct to genetic selection, not a substitute. ## Uncertainty and Sustainability Flushing recommendations are largely empirical and derived from studies conducted under temperate, pasture-based systems. The __MASK_27__ (1962) established the principle that moderate weight gain before mating improves lambing percentage, but the optimal rate and duration of gain remain uncertain for diverse environments. In semi-arid regions, __MASK_28__ found that flushing during summer improved reproductive performance in Malpura ewes, but the same protocol may cause heat stress in breeds adapted to cooler climates. Producers should adjust flushing strategies based on local feed availability and climate projections. From a sustainability perspective, flushing with grain-based concentrates increases the carbon footprint of lamb production because concentrate production requires more inputs than forage. Whenever possible, use high-quality pasture or forage legumes (e.g., chicory, lucerne) as the flushing feed. This approach aligns with __MASK_29__ guidance on integrated crop-livestock systems. Flushing should not exceed 4 weeks, prolonged high-energy feeding increases body condition beyond the optimal range (BCS 3.0,3.5) and can reduce conception rates in subsequent breeding cycles. Regularly review flock records to determine whether flushing generates a consistent return on investment. If no improvement in lambing percentage is seen over two seasons, discontinue the practice and investigate other management or genetic factors. ## Frequently Asked Questions **1. How long should the flushing period last?** Flushing is typically applied for 2 to 4 weeks immediately before introducing rams. Longer periods may oversupply energy and cause excessive fat deposition, which reduces ovulation rate. **2. Can flushing be done on mature ewes only?** No, flushing can be applied to ewes of all ages, but response varies. Ewes with moderate condition (BCS 2.5,3.0) respond best, overconditioned ewes rarely benefit and may experience negative health effects. **3. Does flushing improve lamb survival or only pregnancy rate?** Flushing primarily increases ovulation and pregnancy rate. Lamb survival depends on birth weight, maternal nutrition during mid-gestation, and postpartum management, not directly on pre-breeding feeding. **4. What if a ewe refuses the flushing ration?** Refusal may indicate spoiled feed, incorrect ingredient, or illness. Remove the ewe from the flushing group, check for fever or diarrhea, and consult a veterinarian before reintroducing the ration. **5. Should flushing be combined with ram exposure?** Yes, the “teaser ram effect” or sudden introduction of vasectomized rams before the breeding season can synchronize estrus and amplify the flushing response. However, ensure rams are certified free of venereal diseases. **6. Is flushing safe during hot weather?** Flushing with concentrates can increase metabolic heat production. In hot climates, feed during the cooler morning hours and provide ample shade and water to reduce heat stress risk. **7. Can flushing replace the use of fixed-time artificial insemination?** No, flushing is a nutritional management tool, it does not control ovulation timing. For FTAI programs, hormonal synchronization is required regardless of nutritional status. **8. How do I know if flushing worked?** Ultrasound pregnancy diagnosis at 35,40 days post-mating and recording the lambing percentage will confirm the effect. Compare results to a control group that did not receive flushing. ## Veterinary Notice Flushing is a short-term, high-risk nutritional intervention that demands close oversight. Sudden dietary changes can precipitate ruminal acidosis, enterotoxemia, or pregnancy toxemia in late-gestation ewes if protocols are extended or applied incorrectly. This article provides foundational knowledge, it does not substitute for a veterinary flock-health plan. Each operation should tailor flushing duration and ration composition based on body condition scoring, forage quality, and veterinary assessment. For persistent infertility or suspected metabolic disease, consult a licensed veterinarian. ## At a Glance | Aspect | Summary | |--------|---------| | Purpose of flushing | Increase ovulation rate and litter size by improving ewe energy balance and body condition before breeding. | | Timing | Begin 2 to 3 weeks before ram introduction, continue through the first 2 to 3 weeks of the breeding period. | | Feed types | Energy-dense forages, grain concentrates, or a combination, decide based on forage quality, cost, and ewe body condition. | | Daily intake targets | Provide a gradual increase (not abrupt) to approximately 1.5 to 2.0 times maintenance energy requirements for the flush period. | | Duration limits | Limit the flushing period to 4 to 6 weeks total, prolonged flushing can cause excessive fat deposition and reduce fertility. | | Body condition score | Ideal pre,flushing condition is 3.0 to 3.5 on a 1 to 5 scale, avoid flushing ewes in overcondition (>3.5) to prevent metabolic issues. | | Monitoring requirements | Weekly visual appraisal of body condition and feed adjustment, confirm that feed is consumed evenly across the group. | | Contraindications | Do not flush ewes that are already in good condition, those with a history of pregnancy toxemia, or during extreme heat or feedlot stress. | ## Nutritional Basis for Flushing ### Energy as the Primary Limiting Nutrient Flushing relies on increasing dietary energy density to raise circulating glucose and insulin levels. Higher insulin concentration stimulates ovarian follicular growth and increases the number of ovulations. Energy is the central focus because even moderate underfeeding before breeding reduces conception rates. Producers should evaluate the energy content of their basal forage before adding supplemental feeds. Forages with a total digestible nutrient value below 55 percent may not support the desired energy lift. ### Role of Protein and Minerals Crude protein levels in the flush ration should match the ewe’s stage of production. When forage protein is adequate, additional protein supplementation yields no extra benefit. Excess protein can elevate blood urea nitrogen and impair embryo survival. Trace minerals such as copper, selenium, and zinc support reproductive hormone synthesis. However, mineral supplementation should follow soil and tissue analyses instead of a fixed recipe. Over supplementation of certain minerals can create antagonisms that inhibit absorption. ## Feedstuff Selection and Ration Balancing ### Concentrate versus Forage Approaches Grain concentrates (corn, barley, oats) provide a rapid energy boost and are easy to handle in small amounts. Their low fiber content requires careful introduction to avoid acidosis. Whole grains are often cheaper than processed forms, but processing improves digestibility in older ewes. Forage,based flushing with high,quality legume hay or lush pasture offers a safer alternative because the fiber maintains rumen health. The choice depends on availability, labor, and the ewe’s existing body condition. Mixed rations that combine moderate grain with good forage often produce the most consistent results. ### Managing Feed Changes Abrupt dietary changes cause rumen upset and reduced feed intake. Introduce flush feeds over a 7, to 10,day transition period. Begin by replacing 10 percent of the basal ration with the flush ingredient each day until the target inclusion is reached. During the transition, observe for signs of bloat or diarrhea. If ewes show digestive disturbance, slow the rate of change and increase the fiber component. ## Duration and Timing of the Flush Period ### Pre,Breeding Window The classic flushing period starts 2 to 3 weeks before rams join the flock. This interval allows sufficient time for improved energy status to influence the final stages of follicle growth. Starting too early (more than 4 weeks before) can lead to excessive weight gain and subsequent lower fertility. A short flush of only 1 week often fails to produce a significant ovulation response. Producers should schedule the flush so that peak energy intake coincides with the first 10 to 14 days of breeding. ### Continuation into Breeding Maintaining the flush ration for an additional 2 to 3 weeks after ram introduction supports continued high ovulation rates and helps luteal function. However, once most ewes are bred, reducing energy back to maintenance prevents overcondition. Continuing the high,energy ration for more than 6 weeks increases the risk of dystocia and pregnancy toxemia in late gestation. A stepped,down approach works well: reduce grain by 20 to 30 percent each week after the third week of breeding. ## Monitoring Body Condition and Adjusting Intake ### Condition Scoring Protocol Assign body condition scores weekly during the flush period. Scores of 2.5 or lower indicate insufficient energy reserves, these ewes need a higher intake or a more concentrated feed. Scores of 3.5 or higher signal that the ewe has adequate reserves and further flushing may be counterproductive. Remove overcondition ewes from the flush group and return them to a maintenance ration. For ewes at ideal condition (3.0 to 3.5), provide only enough additional energy to hold condition stable until breeding ends. ### Adjusting for Group Variation Because ewes within a flock vary in age, dominance, and metabolic rate, a single flush ration may not suit all individuals. Consider sorting ewes into condition subgroups. Heavier ewes receive lower energy allocation, while thin ewes receive higher energy. Limit feeding systems that deliver a fixed amount per ewe per day help control variability. Group feeding ad libitum works only when all ewes are of similar condition and intake can be monitored. ## Common Feed Planning Pitfalls ### Over,Reliance on Grain Using grain as the sole flush feed often leads to fat ewes and metabolic disturbances. Grain provides energy but lacks fiber, protein, and essential fatty acids. The rapid fermentation in the rumen can drop pH and reduce fiber digestion from forage. When grain is the primary flush ingredient, keep its proportion below 40 percent of the total dry matter and include a buffer source such as sodium bicarbonate if acidosis is a concern. ### Neglecting Water and Mineral Access Flush rations that are high in dry matter reduce voluntary water intake. Water consumption must increase to compensate for the lower moisture content of concentrated feeds. Provide clean water within easy reach and monitor intake if weather is hot. Mineral supplements can become less palatable when mixed with grain. Offer separate mineral feeders or ensure the total mixed ration contains balanced levels of salt, calcium, and phosphorus. ## Frequently Asked Questions **1. Can flushing work on ewes that are already in good body condition?** Flushing produces the greatest response in ewes with moderate body condition (score 3.0). Overcondition ewes (score 4.0 or higher) rarely show improved ovulation and may experience reduced fertility due to metabolic stress. **2. How much extra feed should I give per ewe per day during flushing?** The exact amount depends on forage quality and ewe size. A general starting point is an increase of 0.5 to 1.0 pound of concentrate per ewe per day, adjusted according to body condition change over the first week. **3. Is it necessary to flush every year?** Flushing is most useful when forage quality is marginal, ewes are in moderate condition, and the goal is to maximize lamb crop from a short breeding season. In flocks with consistent high,quality pasture, routine flushing may not be needed. **4. Can flushing cause pregnancy toxemia?** Flushing that continues beyond the first 3 weeks of breeding or that results in rapid, excessive weight gain can set the stage for pregnancy toxemia in late gestation. The risk increases in obese ewes and during periods of cold stress. **5. What is the best flush feed available at low cost?** Good,quality legume hay (alfalfa, clover) often provides the most economical energy lift when pasture is poor. In areas where grain is cheap, whole oats or barley with a small amount of protein supplement can work well. **6. Should I flush ewes that are grazing lush spring pasture?** Lush pasture may already supply energy above maintenance. Additional flushing in that situation could overshoot condition targets. Evaluate the pasture’s energy density and body condition before deciding. **7. How do I know if flushing has worked?** Compare lambing rates from flushed ewes with those from [a control group](/blog/guides/understanding-control-groups-in-clinical-trials-types-and-selection) that received only the basal ration. Record the number of lambs born per ewe exposed. A increase of 0.2 to 0.5 lambs per ewe is a realistic goal. **8. Can flushing affect ram fertility?** Flushing is normally applied to ewes only. Rams should be maintained in good condition throughout the breeding season. Overfeeding rams can reduce libido and sperm quality. Separate rams from the flush ration intended for ewes. ## Related Farming Guides - [Sheep Farming Flock Nutrition Grazing Lambing Parasite Risk And Welfare](/knowledge/animal-farming/sheep/sheep-farming-flock-nutrition-grazing-lambing-parasite-risk-and-welfare) - [Pasture Management For Sheep](/knowledge/animal-farming/sheep/pasture-management-for-sheep) - [Integrated Parasite Management In Sheep](/knowledge/animal-farming/sheep/integrated-parasite-management-in-sheep) - [Sheep Farm Biosecurity Plan](/knowledge/animal-farming/sheep/sheep-farm-biosecurity-plan) - [Farm Health Intelligence Observation Records Biosecurity Diagnostics And Veterinary Escalation](/knowledge/animal-farming/farm-management/farm-health-intelligence-observation-records-biosecurity-diagnostics-and-veterinary-escalation) ## Related Clinical & Scientific Guides * [Sheep Grazing Lease: Terms, Rates, and Legal Considerations](/knowledge/animal-farming/sheep/sheep-grazing-lease-terms-rates-and-legal-considerations) * [Sheep Breed Selection for Meat, Wool, Dairy, and Low-Input Systems](/knowledge/animal-farming/sheep/sheep-breed-selection-for-meat-wool-dairy-and-low-input-systems) * [Sheep Barn Flooring for Hoof Health: Best Materials and Practices](/knowledge/animal-farming/sheep/sheep-barn-flooring-hoof-health-materials-practices) ## References and Further Reading - [FAO Animal Production and Health](https://www.fao.org/animal-production/en/) - [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/) - [USDA APHIS Livestock and Poultry Disease](https://www.aphis.usda.gov/livestock-poultry-disease) - [Merck Veterinary Manual](https://www.merckvetmanual.com/) - [USDA National Animal Health Monitoring System](https://www.aphis.usda.gov/livestock-poultry-disease/nahms) > This article is educational and is not a substitute for veterinary diagnosis, treatment, public-health guidance, or regulatory reporting.